1. Field of the Invention
The present invention relates to a method and a system for detecting a vehicle position by employing a polarization image.
2. Description of the Related Art
In the fields of vehicle detection, hypothesis generation, polarization, image processing, etc., as a key step of vehicle detection, a hi efficient vehicle position generating approach may extremely increase the detection rate of a whole vehicle detecting system, and may reduce the misrecognition rate thereof.
In the following cited reference No. 1 titled as “A Device For Detection Of Surface Condition Data”, a device for detecting properties or conditions of surfaces like water, snow, ice, etc., is disclosed. Two kinds of reflection are determined by using the following phenomenon: after polarized light is specularly reflected by ice or water on the surface of an object, the polarized nature may be kept, whereas after the polarized light is diffusely reflected by other kinds of surfaces, the polarized nature may be extremely weakened. The main thought of the cited reference No. 1 is emitting light, then detecting the reflection of the light, and then determining the surface condition of an object on the basis of the polarized nature of the reflected light.
In the following cited reference No. titled as “Polarametric Blind Spot Detector With Steerable Beam”, a blind spot detection system is disclosed. The blind spot detection system includes a transmitter directing a circularly polarized signal into a blind spot adjacent to a vehicle; a receiver mounted on the vehicle, receiving a reflection of the circularly polarized signal which is oppositely circularly polarized; and an indicator indicating to the driver of the vehicle when the reflected signal is detected, thereby indicating the presence of an object in the blind spot. The main thought of the cited reference No. 2 is emitting polarized light toward a blind spot, then trying to detect the reflection of the polarized light, and then determining, if the reflection of the polarized light is detected, that an object in the blind spot is detected.
In the above described conventional techniques, it is mentioned that polarized light is utilized to detect an object. However, the two references only relate to a simple way of transmitting and receiving signals, and both of them need to actively emit polarized light, and to detect its reflection. In other words, these kinds of approaches cannot be directly applied to detection of an object in an image.
Furthermore, in the conventional vehicle detecting systems, visible light is mainly used for detection. However, compared to polarized light, the visible light is not robust with regard to various lighting conditions, weather, road surface conditions, etc.
Cited Reference No. 1: International Patent Application Publication No. WO 2004/081897 A2
Cited Reference No. 2: US Patent Application Publication No. 2002/0011926 A1